Characteristics of the study population
A total of 405 children with a mean (SD) age of 6.31(3.54) years, and of both sexes; males (48.9%, 198) and females (51.1%, 207) residing in Batoke-Limbe participated in the study. The ITN ownership (N) was 78.8% (319) with a utilisation of 50.9 % (206). Most of the parents/ guardians of the children had a primary level of education (45.9%, 170) with a few (5.1%, 19) having no formal education. The proportion of children who effectively used a mosquito net was 29.9% (121), with a great proportion of the nets in good condition (Table 1). The proportion of fever, MP and anaemia in the study population were 7.9 % (32), 46.7 % (189) and 54.6 % (221), respectively as shown in Table 1.
Table 1: Socio-demographic and clinical characteristics of the study population
Parameter
|
% (N)
|
Number of participants
|
100 (405)
|
Mean age (SD) in years
|
6.31 (3.54)
|
Age groups (years)
|
<5
|
37.8 (153)
|
5-9
|
40.2 (163)
|
10-14
|
22 (89)
|
Sex
|
Male
|
48.9 (198)
|
Female
|
51.1 (207)
|
ITN coverage (N)
|
78.8 (319)
|
Educational level of parent/caregiver
|
No formal
|
5.1 (19)
|
Primary
|
45.9 (170)
|
Secondary
|
39.7 (147)
|
Tertiary
|
9.2 (34)
|
Mosquito bed net use
|
Yes
|
50.9 (206)
|
No
|
49.1(199)
|
Effective utilization of bed nets
|
Yes
|
29.9 (121)
|
No
|
70.1 (284)
|
Integrity of Mosquito bed net
|
Good
|
71.6 (290)
|
Acceptable
|
6.9 (28)
|
Torn
|
0.2 (1)
|
Clinical
|
Mean temperature (SD) in °C
|
36.71 (0.69)
|
Fever prevalence
|
7.9 (32)
|
Malaria parasite prevalence
|
46.7 (189)
|
Mean haemoglobin level (SD) in g/dL
|
10.95 (2.10)
|
Anaemia prevalence
|
54.6 (221)
|
Malaria parasite prevalence and density
Overall, prevalence of malaria parasitaemia (MP) in the study population was 46.7% (189/405) and majority of the children had a low (74.6%, 141) followed by moderate (20.0%, 38) and high parasitaemia (5.4%, 10). As shown in Table 2, MP prevalence was similar between males (44.9%) and females (48.3%). A significant difference (P = 0.03) was observed with age, with the 5-9 years age group having the highest prevalence (54.6%). In addition, a significant difference (P = 0.02) was observed in the parasite density with respect to age; with the <5 years age group having the highest geometric mean parasite density (GMPD)/µL of blood (537) and the least observed in the 10-14 years age group (319). Children who did not use ITNs as well as those whose ITNs were torn had a higher prevalence of MP than their respective counterparts although not statistically significant (Table 2).
Table 2: Malaria parasite prevalence and density with respect to sex, age, and ITN use
Parameter
|
No. examined
|
Prevalence (n)
|
P-value
|
Parasite density (parasites/µL of blood
|
P –Value
|
GMPD/µL
|
Range
|
Gender
|
Male
|
198
|
44.9 (89)
|
P = 0.50c
|
433
|
100-10920
|
0.56a
|
Female
|
207
|
48.3 (100)
|
464
|
104-11520
|
Age group in years
|
<5
|
153
|
41.2 (63)
|
P = 0.03*c
|
538
|
104-11520
|
0.02*a
|
5-9
|
163
|
54.6 (89)
|
456
|
100-10920
|
10-14
|
89
|
41.6 (37)
|
319
|
100-5740
|
ITN ownership
|
Yes
|
319
|
45.5(145)
|
P =0.346c
|
474
|
100-11520
|
0.65a
|
No
|
86
|
51.2 (44)
|
376
|
100-10920
|
ITN usage
|
Yes
|
206
|
44.2 (91)
|
P = 0.306c
|
431
|
107 – 9300
|
0.63a
|
No
|
199
|
49.2 (98)
|
468
|
100-11520
|
Integrity of ITN
|
Good
|
290
|
45.9 (133)
|
P = 0.438c
|
483
|
100-11520
|
0.807b
|
Acceptable
|
28
|
39.3 (11)
|
416
|
138-1890
|
Torn
|
1
|
100 (1)
|
170
|
170-170
|
*Statistically significant at P < 0.05, aDifference in GMPD determined by Mann-Whitney
bDifference in GMPD determined by Krustal-Wallis
cDifference in proportions determined by Chi square
Prevalence and severity of anaemia
The overall prevalence of anaemia was 54.6%. The prevalence of anaemia decreased significantly (P < 0.001) with an increase in age group. Contrarily, the youngest age group (<5 years) had the highest prevalence of severe anaemia (5.2%), than those older (5-9 and 10-14 years) although the difference was not significant as shown in Table 3. MP positive children and those who presented with fever had higher prevalence of anaemia (70.4% and 62.5%) than their respective negative counterparts. However, only the difference in prevalence by MP status was significant (P < 0.001). On the severity of anaemia, the proportion of MP positive children with severe to moderate anaemia was significantly lower (χ2 = 7.17, P = 0.03) than their negative counterparts. Similarly, the proportion of afebrile children with moderate and mild anaemia was significantly higher (χ2 = 10.65, P = 0.005) than in the febrile children as shown in Table 3
Table 3. Prevalence of anaemia and its severity as affected by age, malaria parasite and fever statuses
Variable
|
N
|
Anaemia
|
Chi square
P-value
|
Anaemia severity
|
Chi square P-value
|
N
|
Severe % (n)
|
Moderate % (n)
|
Mild %(n)
|
Age Group
|
<5
|
153
|
63.4 (97)
|
16.28
< 0.001***
|
97
|
5.2
(5)
|
55.7
(54)
|
39.2 (38)
|
4.47
0.35
|
5-9
|
163
|
55.8 (91)
|
91
|
2.2
(2)
|
56.0
(51)
|
41.8 (38)
|
10-14
|
89
|
37.1 (33)
|
33
|
0
(0)
|
45.5
(15)
|
54.5 (18)
|
Malaria parasite
Status
|
Positive
|
189
|
70.4 (133)
|
35.70
<0.001***
|
133
|
2.3
(3)
|
48.1
(64)
|
49.6 (66)
|
7.17
0.03*
|
Negative
|
216
|
40.7 (88)
|
88
|
4.5
(4)
|
63.6
(56)
|
31.8 (28)
|
Fever status
|
Febrile
|
32
|
62.5 (20)
|
0.88
0.36
|
31
|
12.9 (4)
|
48.4
(15)
|
38.7 (12)
|
10.65
0.005*
|
Afebrile
|
373
|
53.9 (201)
|
183
|
1.6
(3)
|
56.3 (103)
|
42.1 (77)
|
*Statistically significant at P < 0.05, **statistically significant at P < 0.01, ***statistically significant at P < 0.001.
ITN ownership, utilisation rates and malariometric indices
As shown in Fig 2, although not significant, the proportion of females with ITN (79.2%) and females who slept under bed nets (52.7%) were greater than the males while, with age the ownership and utilization was higher in the <5 years age group than counterparts. Also, ownership and utilization of ITN among anaemic and non-anaemic children was comparable.
The proportion of ineffective users was significantly higher (χ2=26.08, P<0.001) in children who were malaria parasite positive (54.9%) than negative (27.3%) as shown in Figure 3.
The mean MP density was comparable between ITN users (2.63 parasite/µL of blood) and non ITN users (2.67 parasite/µL of blood). However, the mean MP density was lower (t = -5.138, P < 0.001) among children who effectively used ITN (2.24 parasite/µL of blood) compared to those who didn’t (2.74 parasite/µL of blood) as seen in Figure 4.
Knowledge and malaria parasite status
The overall appropriate knowledge on malaria was 40.7%. As shown in Table 4, there was a significant association (P<0.001) between knowledge of malaria and MP parasite status. The proportion of MP positive cases whose parents/caregivers had appropriate knowledge on malaria (30.7%) was significantly lower than their negative counterparts (49.5%). The level of appropriate knowledge of malaria decreased significantly (P = 0.001) with the level of education of parents/caregivers of the children (tertiary: 61.8% and no formal:21.1%) as shown in Table 7.
Table 4: Effects of clinical and demographic factors on malaria knowledge
Variable
|
N
|
Malaria knowledge % (n)
|
χ2
P
|
Appropriate
|
Inappropriate
|
Asexual malaria
Parasite status
|
Negative
|
216
|
49.5 (107)
|
50.5 (109)
|
14.834
< 0.001***
|
Positive
|
189
|
30.7 (58)
|
69.3 (131)
|
Age group of parents/caregivers
|
<30
|
143
|
34 (49)
|
66 (74)
|
5.85
0.05
|
31-40
|
172
|
43.2 (74)
|
56.8 (98)
|
>40
|
90
|
49.0 (41)
|
51.0 (46)
|
Educational level of parents
/caregivers
|
No formal
|
19
|
21.1 (4)
|
78.9 (15)
|
13.26
<0.001***
|
Primary
|
170
|
34.7 (59)
|
65.3 (111)
|
Secondary
|
147
|
45.6 (67)
|
54.4 (80)
|
Tertiary
|
34
|
61.8 (21)
|
38.2 (13)
|
*Statistically significant at P < 0.05, ***Statistically significant at P < 0.001.
Malaria parasite, ITN, knowledge and haematological indices
The effect of malaria parasite on haematological indices is presented in Additional file 1 where, significantly lower Hb levels (P < 0.001), Hct (P < 0.001), and RBC counts (P < 0.001) were observed in malaria parasite positive children than negative. Also, children who used ITN had significant higher mean Hb levels (P=0.032), RBC count (P=0.009), MCHC (P=0.039), RDW-CV (P=0.036) and PLT count (P=0.007) compared to those who did not use ITN as shown in additional file 2.
Using a multilinear regression model with each haematological variable as the dependent variable, to examine the influence of age, sex, knowledge on malaria, ITN use, effective ITN use and MP status on each haematological variable; it was observed that age negatively correlated with WBC (P < 0.001) and positively correlated with Hb (P = 0.013), MCV (P < 0.001) and MCH (P < 0.001). Malaria knowledge negatively correlated with WBC (P = 0.005) but positively correlated with Hb levels (P < 0.001), RBC counts (P < 0.001), Hct (P < 0.001), MCV (P < 0.001) and MCH (P < 0.001). Similarly, ITN use positively correlated with WBC counts (P = 0.005) but negatively correlated with Hb levels (P = 0.004), RBC counts (P = 0.006), and MCH (P < 0.001). In addition, a significant negative correlation of effective ITN use with WBC (P = 0.006) was observed. Furthermore, MP negatively correlated with Hb levels (P = 0.004), RBC counts (P = 0.01), Hct (P = 0.04) and MCHC (P = 0.015) as shown in (Table 5).
Table 5: Multiple linear regression analyses examining the influence of independent variables on each haematologic measure
Haematological Parameter
|
Mean (SD)
|
Independent variable
|
β value
|
P value
|
Partial correlation
|
R2
|
WBC × 109/ L
|
7.9 (3.7)
|
Age
|
-0.28
|
< 0.001***
|
-1.39
|
0.14
|
Sex
|
0.03
|
0.484
|
0.25
|
Knowledge
|
-0.13
|
0.005**
|
-1.02
|
ITN use
|
0.18
|
0.003**
|
1.37
|
Effective ITN use
|
-0.17
|
0.006**
|
-1.42
|
Malaria parasite
|
0.08
|
0.124
|
0.57
|
Hb (g/dl)
|
11.0 (2.0)
|
Age
|
0.11
|
0.013*
|
2.95
|
0.26
|
Sex
|
0.01
|
0.830
|
0.38
|
Knowledge
|
0.46
|
<0.001***
|
19.3
|
ITN use
|
-0.17
|
0.004**
|
-6.80
|
Effective ITN use
|
0.09
|
0.143
|
3.86
|
Malaria parasite
|
-0.15
|
0.004**
|
-2.01
|
RBC× 109/ L
|
5.0 (1.1)
|
Age
|
-0.04
|
0.358
|
-0.06
|
0.14
|
Sex
|
0.03
|
0.481
|
0.07
|
Knowledge
|
0.32
|
<0.001**
|
0.67
|
ITN use
|
-0.17
|
0.006**
|
-0.35
|
Effective ITN use
|
0.06
|
0.390
|
0.122
|
Malaria parasite
|
-0.16
|
0.01**
|
-0.126
|
Hct (%)
|
36.1 (7.4)
|
Age
|
0.07
|
0.133
|
0.66
|
0.22
|
Sex
|
0.03
|
0.495
|
0.45
|
Knowledge
|
0.42
|
<0.001**
|
6.33
|
ITN use
|
-0.11
|
0.07
|
-1.56
|
Effective ITN use
|
0.03
|
0.585
|
0.53
|
Malaria parasite
|
-1.63
|
0.04*
|
-1.14
|
MCV/ (fl)
|
74.2 (8.7)
|
Age
|
0.16
|
0.001***
|
1.86
|
0.08
|
Sex
|
-0.06
|
0.220
|
-1.03
|
Knowledge
|
0.17
|
<0.001***
|
3.06
|
ITN use
|
0.09
|
0.169
|
1.52
|
Effective ITN use
|
-0.05
|
0.473
|
-0.89
|
Malaria parasite
|
-0.05
|
0.310
|
-0.91
|
MCH/pg
|
22.6 (2.5)
|
Age
|
0.26
|
<0.001***
|
0.86
|
0.13
|
Sex
|
-0.05
|
0.324
|
-0.23
|
Knowledge
|
0.21
|
<0.001***
|
1.05
|
ITN use
|
-0.05
|
0.456
|
-0.23
|
Effective ITN use
|
0.02
|
0.780
|
0.10
|
Malaria parasite
|
-0.01
|
0.924
|
-0.02
|
MCHC (g/L)
|
305.9 (27.1)
|
Age
|
0.09
|
0.063
|
3.31
|
0.04
|
Sex
|
-.01
|
0.923
|
-0.26
|
Knowledge
|
0.08
|
0.105
|
4.51
|
ITN use
|
-0.16
|
0.017*
|
-8.45
|
Effective ITN use
|
0.10
|
0.153
|
5.68
|
Malaria parasite
|
0.13
|
0.015*
|
6.94
|
0.11
|
RDW-CV/%
|
15.9 (3.6)
|
Age
|
0.23
|
0.001***
|
1.03
|
Sex
|
0.09
|
0.049*
|
0.67
|
Knowledge
|
-0.04
|
0.403
|
-0.30
|
ITN use
|
-0.29
|
0.001***
|
-2.05
|
Effective ITN use
|
0.30
|
0.001***
|
2.32
|
Malaria parasite
|
0.10
|
0.060
|
0.68
|
Plt/L
|
328.1 (141.1)
|
Age
|
o.15
|
0.003**
|
28.04
|
0.04
|
Sex
|
0.02
|
0.765
|
4.15
|
Knowledge
|
0.02
|
0.733
|
4.94
|
ITN use
|
-0.19
|
0.004**
|
-52.25
|
Effective ITN use
|
0.09
|
0.194
|
26.81
|
Malaria parasite
|
0.04
|
0.932
|
1.27
|
*Statistically significant at P < 0.05 **Statistically significant at P < 0.01 ***Statistically significant at P < 0.001